Field of the Invention
The present invention relates to a system for controlling stability in heavy machinery, providing essential features of novelty and significant advantages with respect to means that are known and used for the same purposes in the current state of the art.
More particularly, the invention relates to a system for controlling stability particularly applicable to heavy machinery, particularly to machines of the type including chains or treads for movement thereof, the operation of the system being based on knowing in each instant the reaction value at the support points of the machine on the ground, based on which the moments of rollover of the machine with respect to a closed polygonal enclosure provided by the actual support points of the machine on the support surface will be determined, as well as the determination of the rollover reversibility characteristic based on analyzing the value of the moment generated by the gravitational forces acting on the system around one of the sides of the closed polygonal enclosure on which the machine is supported. The field of application of the invention is comprised in the industrial sector dedicated to the development and installation of static and dynamic security systems in heavy machinery, particularly machines for public works and the like that are moved with chains or treads.
Description of the Related Art
A wide variety of devices and methods are known in the current state of the art intended for determining the risk of rollover of a machine or a vehicle of any type during the normal use thereof both in static and dynamic conditions, either as a result of the use made of same or as a result of other effects derived from or induced by situations not related to the vehicle itself (for example, traffic accidents or the like). In most devices and/or methods of the current state of the art, determination of a possible rollover situation is performed by means of using several sensors which are generally tilt sensors located in several positions of the vehicle, detecting and measuring parameters related to the verticality conditions of certain members of the vehicle, and generating signals which are processed and compared with pre-established threshold values considered as acceptable limits for assuring vehicle safety. Normally, the mentioned parameters are obtained based on measuring angles related to the rolling and/or tilt of the vehicle, such that when these angles of rolling and/or tilt exceed such pre-established thresholds, situation of risk of rollover is considered and a plurality of reactions is generated ranging from a simple alarm that warns the user or the control means about the occurring situation by means of light and/or sound signals, to the activation of other safety elements for counteracting the possible rollover situation, such as for example, activation of the front and/or rear brakes of the mover, subsequent reduction of the travel speed, correction of the angles of rotation, extension and deployment of safety means incorporated in the vehicle itself, etc.
However, for machines that perform field works (for example, backhoes intended for soil conditioning functions, agricultural machines, etc.), situations still arise in practice which, albeit generating machine positions that in most cases can lead to tilts exceeding those angles previously considered as operative limits or thresholds, do not however generate an actual risk of rollover. The case of a backhoe-type machine performing soil conditioning works can be mentioned, for example, which as a result of the effort made with the bucket when trying to drive it into the soil, can lead to a reaction causing the machine to be lifted partially with respect to the support edge of the chassis of the machine occupying a position opposite the arm bearing the work bucket, which together with the actual tilt the machine can already be subjected to due to the slopes of the soil surface itself in which it is supported, entails the adoption of a tilt angle surpassing the limits of the pre-established threshold, generating warnings of danger which do not actually constitute an actual risk of rollover, and which however make stopping the function being performed at that moment necessary. All this constitutes drawbacks generating delays, time losses, and increased production costs.
As an illustrative example of rollover prevention systems known and used today in relation to machinery of the mentioned type, the inventors of the system described in the present invention are aware of the existence in the state of the art of some prior art documents that will be described briefly below. Patent document WO 2008/105997 (Caterpillar Inc.) describes an automated rollover prevention system applicable to heavy machinery, intended for controlling the machine remotely and autonomously, in which one or more tilt sensors and/or sensors of other magnitudes is used with which signals indicative of the tilt of the machine are generated such that a controller device can determine stopping of the operation thereof when the tilt of the machine exceeds certain threshold levels, as well as the backward movement of the machine until the known final stable position.
European patent document EP-2492404 A1 (Hitachi Construction Machinery Co., Ltd.) describes a machine particularly useful in construction works, demolition works, civil engineering works and the like, in which it aims to provide stability to the machine at all times by solving the problem associated with the inertia forces derived from the up and down movement with respect to the chassis of the machine, of the mechanism of a front working fitting, or of the movement of the machine itself, evaluating in each instant the stability of the machine and communicating the results of that evaluation to an operator without delays. For such purpose, the machine includes: (i) Zero Moment Point (identified as ZMP) calculating means, using to that end position vectors, acceleration vectors and external force vectors at the respective mass points constituting the main chassis, including the front working mechanism and the undercarriage, and (ii) stability calculating means provided for defining a support polygon joining support points of the work machine with a ground and such that when the ZMP is included in a warning area formed inside a perimeter of the support polygon, producing a rollover warning. The support polygons referred to in patent document EP-2492404 A1 are depicted in FIGS. 5, 7, 8, 9(a), 9(b), 9(c), 9(d), 17(a), 17(b) and 17(c), the support polygons on which the risk regions are determined are depicted in FIGS. 4(a), 4(b), 6(a) and 6(b). However, in all the described examples, the support polygon is determined by the geometry defined by the way the machine is supported (chains, wheels or stabilizers), without the
actual contrast of detector elements allowing precise determination in each instant of the actual support points of the machine on the ground. For this reason, European patent document EP-2492404 A1 (Hitachi Construction Machinery Co., Ltd.) is not applicable on concave support surfaces as described explicitly in line 38 of page 3 of said patent.
Furthermore, experience proves that when working with this type of machines, other situations that are not contemplated in patent document EP-2492404 A1 arise, such as for example, the fact that the machine is not completely supported on the ground, i.e., a part of the machine works on an incomplete surface, with a cantilevered portion, in which case the support polygon cannot be determined by the geometry defined by the way the machine is supported (chains, wheels or stabilizers), the latter being a clearly unstable situation which can entail certain risk of rollover and which the document under consideration does not solve.
European patent document EP-2578757 (Hitachi Construction Machinery Co., Ltd.) having features similar to the document mentioned above, describes a work machine safety system also having the purpose of achieving machine stability based on calculating the coordinates of a ZMP (Zero Moment Point) using to that end information about position, acceleration and external forces acting on the movable portions of the main body of the machine, including the front working mechanism and the undercarriage, incorporating calculating means for determining a polygon going through the theoretical contact points of the machine with the ground, and such that when the ZMP moves through the inside of the enclosure demarcated by said polygon, a rollover warning is produced when ZMP enters a predetermined warning region formed in the lower portion of the polygon. The system envisages the incorporation of means for graphically presenting and displaying the position of the ZMP inside the enclosure, included the warning region, and develops positional calculation algorithms of the ZMP, with predictive capacity with respect to the behavior of said point, and with means for storing information. The system does not describe or suggest a solution for the case in which the machine is not completely supported on the ground, but rather in a partially cantilevered manner with the risks that it entails or for the case in which the support surface is concave.